Structural panels of this kind are generally used as cabin partition walls or side walls of storage cabinets in passenger aircraft. Such panel walls generally comprise a lightweight composite panel core with a visually attractive colorful pattern or image on the surface. The material of which these panels and especially the cover layers of these panels are made, is fiber reinforced composite material. In prior art methods, exposed surfaces which are to receive a colorful patterned coating such as a paint coating must first be prepared by the following steps: grinding the surface; filling the surface pores with a pore filling material; smoothing the filler material; grinding and polishing the filled surface; and base coating.
The various process steps for smoothing the surface of the lightweight composite panels are necessary because the respective cover layers of the composite panels comprise an uneven surface having a waviness caused by the production method of the composite panel. The waviness is caused, because the honeycomb core of the composite panel only supports the cover layers of the composite panel in the areas of the honeycomb walls and not in the hollow core spaces or voids, so that depressions or dimples are formed in the cover layer in the areas of the honeycomb voids or hollow spaces. The machining steps for planing or smoothing the surface of such panels are very time consuming and greatly increase the production costs. Making the surface of such honeycomb panels smooth also requires thicker cover layers than would be needed if the depressions or dimples may remain visible. It is a considerable disadvantage of the prior art method that the colorful attractive pattern or image layer can only be applied after the surface of the panel has been prepared in the above mentioned smoothing or planing steps if the dimples are to be avoided.